by Renato Morano
(Manila, Philippines)

I have a 1Hp 230VAC 60Hz National split type wall mount room air conditioner. It's been working well for quite few years now. Recently I experienced the system is having trouble. The compressor and fan(outdoor unit) is running while cooling the room for about 5 min. then shuts off. While the indoor unit keeps on running.

When the air gets warmer for about 2 min. the compressor & fan starts pumping cool air again. This happens continuously until I turn the unit off. I have checked the two Thermistors and found the coil sensor has reading on multi-amp tester only 2K Ohms. The air sensor has reading of 12K ohms. So I changed the coil sensor with a new one.

After this step I run the air con but the same problem still exist. The caps installed are 15uF on the compressor while 2uF on the fan respectively. I checked the caps of the compressor and fan respectively and shows on the multi-amp tester to be 14.43Uf and 1.9Uf respectively. So think both caps are still good.

However, I tried to run the system and took the voltage across the hot terminals of the two caps and got a reading of 342V. on compressor capacitor and 314V. on the fan cap.

This shows over-voltage and what's causing it is my next step to do. This most likely will involve the control card. May I have your analysis or comment on this problem please.

Thank you,
Ren Morano

Comments for Entrepreneur

Average Rating starstarstarstarstar

Click here to add your own comments

Jun 16, 2018
Possible Causes
by: Michael

Hi Ren,

Based on your description, your air conditioner could be an inverter type air conditioner. The unit could be working fine as the room was being cooled when needed to.

If it is an inverter type, the frequency of the compressor will rotate based on the demand of the load. Check your settings on your remote again. Set it to COOL Mode, 24°C and test again. Read more here.

When you changed the thermistors, make sure they are the same type as the original or else the operations will go out. Check out about thermistor here.

The voltages at the capacitors seem to be fine if it is an inverter unit. Read more and notice the rectifier circuit which explains the higher voltages that you get.

Hope that helps.

Click here to add your own comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Share Your Air Conditioning Experience.

Energy Saving Tips       Refrigerant      IAQ      Motors      Humidifier

  Cooling Load    Leak Detection     HVAC Scholarships    Filter Drier

  HVAC Contests      3D Printing      Air Filter      Pumps    AHU  

HVAC Manufacturers    Air Conditioner Ratings       Radon

Split AC Brands    Smart Thermostats   DX System